JP2012106357A - Printing device and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique to suppress refill delay with a method different from the conventional one.SOLUTION: A printing device for carrying out printing with ink supplied from L pieces of ink cartridges in which ink of the same hue is accommodated. The printing device includes a print head with a plurality of nozzle rows where a plurality of nozzles are arrayed in a sub scanning direction. The print head includes a first nozzle group of L×(a) nozzle rows having correlation on printing, in which the positions of the respective nozzles in the sub scanning direction are the same, and which receive supply of the ink from each of the L pieces of cartridges by (a) rows, and a second nozzle group which comprises L×(b) pieces of nozzle rows in which the positions of the nozzles in the sub-scanning direction differ from those of the first nozzle group and nozzle rows which receive supply of the ink from each of the L pieces of cartridges by (b) pieces. A control unit performs control to limit the number of nozzles to eject the ink at the same time, in each nozzle row of (a)+(b) to which the ink is supplied from each of L pieces of cartridges.

Description

  The present invention relates to a printing apparatus, and more particularly to a printing apparatus that performs printing by receiving ink supplied from a plurality of ink cartridges that store ink of the same hue.

  In the printing apparatus, when the amount of liquid supplied from the cartridge to the nozzle is smaller than the amount of ink discharged from the nozzle, that is, the ink refill speed is slow (hereinafter also referred to as “refill delay”). In such a case, there is a problem that an ink ejection failure occurs in the nozzle. As a technique for suppressing the refill delay, for example, the technique of the following patent document is known.

JP 2009-274280 A JP 2009-274281 A

  The technique of the above-mentioned patent document suppresses refill delay by analyzing image data to be printed. An object of this invention is to provide the technique which suppresses a refill delay by the method different from the past.

  In order to solve at least a part of the problems described above, the present invention can take the following forms or application examples.

[Application Example 1]
A printing apparatus that performs printing upon receiving ink supplied from L (L is an integer of 2 or more) ink cartridges that store ink of the same hue, wherein a plurality of nozzles that eject the ink are arranged in a predetermined direction A print head including a plurality of nozzle rows spaced apart from each other in a direction intersecting the direction; a main scanning direction that is a separation direction of the nozzle rows relative to the print medium; and And a control unit that controls ejection of the ink from the nozzles, and the print head has the same position in the sub-scanning direction of the arranged nozzles. L × a rows (a is an integer equal to or greater than 1) nozzle rows having a predetermined correlation in printing under the control of the control unit, and each of the L cartridges is a row by row. L × b different from the nozzles belonging to the first nozzle group, and the positions of the arranged nozzles in the sub-scanning direction are different from the nozzles belonging to the first nozzle group. (B is an integer equal to or greater than 1) nozzle rows, and each of the b nozzle rows includes a second nozzle group including a nozzle row that receives the supply of ink from each of the L cartridges. The control unit is a printing apparatus that performs control to limit the number of nozzles that simultaneously eject ink in each of the a + b nozzle rows in which each of the L ink cartridges supplies the ink.

  According to this printing apparatus, the control unit performs control to limit the number of nozzles that simultaneously eject ink in each of the a + b nozzle rows to which each of the L ink cartridges supplies ink. It is possible to suppress the delay.

[Application Example 2]
In the printing apparatus according to application example 1, each of the plurality of nozzle rows has an equal nozzle pitch in the sub-scanning direction, and the nozzle rows of the first nozzle group and the nozzle rows of the second nozzle group are A printing apparatus in which the arrangement positions of the nozzles in the sub-scanning direction are different from each other by 1 / (L × b + 1) of the nozzle pitch.

  According to this printing apparatus, it is possible to print a print image with a resolution higher than the resolution corresponding to the nozzle pitch for each nozzle row.

[Application Example 3]
3. The printing apparatus according to application example 1 or claim 2, wherein the control unit is configured such that the formation positions of the ink dots based on the nozzle rows belonging to the first nozzle group are exclusive between the nozzle rows. A printing apparatus that performs the control so as to have compatibility.

  According to this printing apparatus, the nozzles belonging to each nozzle row of the first nozzle group are arranged at the same position in the sub-scanning direction between the nozzle rows. In addition, since the control unit controls the formation position of each ink dot based on each nozzle row so as to be exclusive and compatible between the nozzle rows, the dots formed based on the nozzles of the first nozzle group are The nozzle row of the first nozzle group can be selected and determined.

[Application Example 4]
The printing apparatus according to any one of application examples 1 to 3, wherein the value of L is 2, the value of a is 1, and the value of b is 1.
According to this printing apparatus, the structure of the printing apparatus can be reduced in size.

[Application Example 5]
A printing method using a printing apparatus that performs printing by receiving ink supplied from L (L is an integer of 2 or more) ink cartridges containing ink of the same hue, wherein the printing apparatus ejects the ink A plurality of nozzle rows in which a plurality of nozzles arranged in a predetermined direction are spaced apart from each other in a direction intersecting the direction, a print head, and a control unit that controls ejection of ink from the nozzles, and a print medium Relative to the main scanning direction, which is the separation direction of the nozzle rows, and the print head that scans in the sub-scanning direction, which is the arrangement direction of the nozzles, and among the plurality of nozzle rows, The nozzle rows of L × a rows (a is an integer of 1 or more) having the same correlation in printing in the sub-scanning direction and having a predetermined correlation in printing by the control from the control unit are: Each row, said L The first nozzle group that receives the ink supply from each of the cartridges, and the positions of the arranged nozzles in the sub-scanning direction differ from the nozzles of the first nozzle row by L × b. (B is an integer of 1 or more) nozzle arrays each including the b nozzle groups and the second nozzle group that receives the ink supply from each of the L cartridges, and the L ink cartridges A printing method in which printing is performed by limiting the number of the nozzles that simultaneously eject the ink in each of the a + b nozzle rows to which the ink is supplied.

  According to this printing method, printing is performed by limiting the number of nozzles that simultaneously eject ink in each of the a + b nozzle rows to which each of the L ink cartridges supplies ink. Can be suppressed.

  Note that the present invention can be realized in various modes. For example, the present invention can be realized in the form of an ink supply method and apparatus, a printing system, an integrated circuit for realizing the functions of the method or apparatus, a computer program, a recording medium on which the computer program is recorded, and the like.

It is explanatory drawing explaining the structure of the printing apparatus 10 as 1st Example. 3 is an explanatory diagram schematically showing a configuration of a print head 50 in the printing apparatus 10. FIG. It is explanatory drawing explaining the mechanism of the supply of ink. 3 is a flowchart illustrating a flow of a printing process performed by the printing apparatus. It is explanatory drawing explaining the discharge nozzle determination table M2. It is explanatory drawing explaining the nozzle number restriction | limiting. It is explanatory drawing explaining the comparative example about nozzle number restriction | limiting. It is explanatory drawing explaining matrix CDMa. It is explanatory drawing explaining matrix CDMb. It is explanatory drawing explaining matrix CDMc. It is explanatory drawing explaining the aspect 1 in the modification 2. FIG. It is explanatory drawing explaining the aspect 2 in the modification 2. FIG. FIG. 10 is an explanatory diagram illustrating a time axis matrix Tm that can be employed in aspect 2.

Next, embodiments of the present invention will be described based on examples.
A. First embodiment:
(A1) Configuration of printing apparatus:
FIG. 1 is an explanatory diagram illustrating a configuration of a printing apparatus 10 as a first embodiment. The printing apparatus 10 is an ink jet printer that prints characters, images, and the like by ejecting ink onto a print medium P based on image data. In the present embodiment, the printing apparatus 10 has various functions such as a scanner and a copy as a so-called multifunction machine. Further, as will be described later, the printing apparatus 10 is a printing apparatus dedicated to monochrome printing that performs printing using only black ink.

  The printing apparatus 10 includes a card slot 12 and a communication connector 13. The card slot 12 of the printing apparatus 10 is an interface that is connected so as to be able to exchange data with a memory card containing a storage medium. The communication connector 13 of the printing apparatus 10 is an interface that connects to an external device such as a personal computer, a digital camera, or a digital video camera so as to exchange data. The printing apparatus 10 is stored in a memory card connected to the card slot 12 or an external device connected to the communication connector 13 in addition to a function of printing based on a print request from an external device connected to the communication connector 13. It has a function of printing existing image data.

  The printing apparatus 10 further includes a scanner unit 11, a display 14, and an operation panel 15. The scanner unit 11 reads a document placed on a document table and converts it into digital data. The display 14 displays characters and images for the user. The operation panel 15 receives an instruction input from the user.

  In addition to the card slot 12 and the communication connector 13 described above, the printing apparatus 10 further includes a control unit 20 that controls each unit of the printing apparatus 10 and a printing mechanism unit 30 that executes printing on the printing medium P. .

  The control unit 20 includes a CPU 21, a RAM 22, and a ROM 23. The CPU 21 includes an image data acquisition unit 24, a monochrome conversion unit 25, a halftone processing unit 26, an ejection nozzle determination processing unit 27, and a print control unit 28. The image data acquisition unit 24 acquires image data from the scanner unit 11, the card slot 12, and the communication connector 13. The monochrome conversion unit 25 performs data conversion to monochrome image data when the acquired image data is RGB image data. The halftone processing unit 26 performs a process of converting the image data into a distribution of dots based on the gradation of the image data subjected to the monochrome conversion. The dither mask M1 stored in the ROM 23 is used for the halftone process. The discharge nozzle determination processing unit 27 discharges ink from which nozzle of the print head 50 described later to each dot of the image data after the halftone process, using the discharge nozzle determination table M2 stored in the ROM 23. Whether to form dots on the print medium P is determined. The print control unit 28 controls the operation of the printing mechanism unit 30 based on the data after processing by the ejection nozzle determination processing unit 27. Each process described above is realized by the CPU 21 reading and executing a program stored in the ROM 23. The dither mask M1 and the discharge nozzle determination table M2 are stored in the ROM 23 in advance.

  As shown in FIG. 1, the printing mechanism unit 30 of the printing apparatus 10 includes a carriage 40, a head unit 41, a carriage drive unit 32, and a transport unit 34. The carriage drive unit 32 drives the carriage 40 in the main scanning (head scanning) direction. The transport unit 34 transports the print medium P in the sub-scanning direction that intersects the main scanning direction in which the carriage 40 moves.

  The carriage 40 holds the head unit 41 and mounts the ink cartridge 42 and the ink cartridge 43. The ink cartridges 42 and 43 mounted on the carriage 40 function as a liquid supply unit that supplies ink to the head unit 41. The ink cartridges 42 and 43 are sealed ink cartridges, and both contain black (BK) ink. In the present embodiment, black and white printing is performed as monochrome printing. For example, the ink cartridges 42 and 43 are, for example, one color such as sepia, red, blue, magenta (M), and cyan (C). Ink may be stored and monochrome printing such as magenta or cyan may be performed. Alternatively, the ink cartridge 42 may contain black (K), the ink cartridge 43 contains light black (LK), and the like.

  The head unit 41 includes a print head 50. The print head 50 includes a plurality of nozzles that eject black (BK) ink. Printing on the print medium P is realized by the print head 50, the carriage drive unit 32, and the transport unit 34 cooperating under the control of the control unit 20.

  FIG. 2 is an explanatory diagram schematically showing the configuration of the print head 50 in the printing apparatus 10. The print head 50 includes a plurality of nozzle rows in which a plurality of nozzles NZ that eject ink (black in this embodiment) are arranged in the sub-scanning direction (that is, the paper feed direction).

  In the present embodiment, the print head 50 includes four nozzle rows of A row, B row, C row, and D row in which a plurality of nozzles NZ are arranged in the sub-scanning direction (that is, the paper feeding direction). These four nozzle rows are arranged in parallel in the main scanning direction as shown in FIG. The A row and the B row are arranged with an interval of 40/360 [inch] in the main scanning direction. Similarly, the C row and the D row are also arranged with an interval of 40/360 [inch] in the main scanning direction. The B row and the C row are arranged with an interval of 104/360 [inch].

  In each of the nozzle rows A, B, C, and D, 128 nozzles NZ are arranged in the sub-scanning direction. In each nozzle row, the interval in the sub-scanning direction between the nozzles NZ (hereinafter also referred to as “nozzle pitch”) is 1/120 [inch]. The position of row B in the print head 50 is arranged at a position shifted by 1/360 [inch] in the sub-scanning direction with reference to the nozzle row of row A. The position of the C row in the print head 50 is arranged at a position shifted by 1/360 [inch] in the sub scanning direction with reference to the nozzle row of the B row. The position of the D row in the print head 50 is arranged at the same position as the nozzle row of the C row in the sub-scanning direction. Accordingly, by performing printing by scanning the print head 50 in the main scanning direction, printing is substantially performed in the same manner as a print head having a nozzle pitch of 1/360 [inch]. The nozzle rows of the C row and the D row correspond to the first nozzle group described in the claims, and the nozzle rows of the A row and the B row correspond to the second nozzle group described in the claims. To do.

  Each of the plurality of nozzles NZ includes a piezo element (piezoelectric element), and ejects ink from the nozzle NZ by vibration due to distortion of the piezo element accompanying application of a voltage to the piezo element. Accordingly, each nozzle NZ includes an electrode for applying a voltage and other elements necessary for ejecting ink in addition to the above-described piezoelectric element. In the present embodiment, when the print head 50 is manufactured, the nozzle unit 52 including the nozzle rows of the A row and the B row and the nozzle unit 53 including the nozzle rows of the C row and the D row are manufactured, respectively. The unit 52 and the nozzle unit 53 are incorporated in the main body of the print head 50.

  Next, a mechanism for supplying ink from the ink cartridges 42 and 43 to each nozzle NZ will be described with reference to FIG. The ink cartridge 42 supplies ink to the nozzles NZ in the A row and the nozzles NZ in the C row. The ink cartridge 43 supplies ink to the nozzles NZ in the B row and the nozzles NZ in the D row. That is, ink is supplied from one cartridge to each of the two nozzle units 52 and 53 provided in the print head 50. In other words, each nozzle unit receives ink supply to each one nozzle row for each ink cartridge. Specifically, as shown in FIG. 3, the nozzle unit 52 is supplied with ink from the ink cartridge 42 to one nozzle row of the A row, and from the ink cartridge 43 to one nozzle row of the C row. Is receiving ink supply. Therefore, the ink supply is not limited to the ink supply mode according to the present embodiment. For example, the ink cartridge 42 supplies ink to the nozzle NZ of the B row and the nozzle NZ of the C row, and the ink cartridge 43 corresponds to the nozzles NZ and D of the A row. It is good also as an aspect which supplies ink to the nozzle NZ.

(A2) Printing process:
Next, a printing process performed by the printing apparatus 10 will be described. FIG. 4 is a flowchart showing the flow of printing processing performed by the printing apparatus 10. When the printing process is started, the CPU 21 acquires image data through the scanner unit 11, the card slot 12, or the communication connector 13 (step S102). If the acquired image data is RGB image data, the image data is converted into monochrome image data (step S104). For example, the image data is converted into monochrome image data by converting it into a K (black) tone value using a color conversion three-dimensional lookup table composed of R, G, and B elements.

  After conversion to monochrome image data, the CPU 21 performs halftone processing on the monochrome image data (step S106). Specifically, the dither mask M1 stored in the ROM 23 is used to convert the gradation value of each pixel of the monochrome image data into binary data. That is, gradation data is converted into dot data by determining whether or not to form a dot for each pixel of the image data. In this embodiment, a systematic dither method known as halftone processing is used. As the halftone process, in addition to the systematic dither method, other halftone techniques such as an error diffusion method and a density pattern method can be used. Since these halftone techniques are well-known techniques, description thereof will be omitted.

  Thereafter, the CPU 21 performs a discharge nozzle determination process on the image data after the halftone process (step S108). As described above, the ejection nozzle determination process is a process for determining from which nozzle ink is ejected to form dots on the print medium for each dot of the dot data after the halftone process. When performing the discharge nozzle determination process, the CPU 21 uses the discharge nozzle determination table M <b> 2 stored in the ROM 23. Hereinafter, the discharge nozzle determination table M2 will be described.

  FIG. 5 is an explanatory diagram for explaining the discharge nozzle determination table M2. FIG. 5 shows the print head 50 and the discharge nozzle determination table M2. Each square of the matrix of the discharge nozzle determination table M2 corresponds to each pixel of the image data. The alphabets A, B, C, and D described in each square indicate which nozzle row (see FIG. 2) the ink is ejected from. For example, the dots on the dot data corresponding to the squares in which “A” is described are printed by ejecting ink from the nozzles in the A row. In the case where “C, D” is written in one square, printing is performed by ejecting ink from nozzles belonging to either the C row or the D row. That is, the positions where the nozzles belonging to the nozzle row C form ink dots and the positions where the nozzles belonging to the nozzle row D form ink dots are in an exclusive relationship.

  In the printing process in this embodiment, each raster line in the print image is printed by one main scan of the print head 50. For example, the raster line R1 shown in the ejection nozzle determination table M2 in FIG. 5 in which the squares marked “A” are arranged in the main scanning direction receives ink from the nozzles NZ1 belonging to the A column shown in the print head 50. By ejecting, ink dots are formed on the print medium P by one main scan of the print head 50 (hereinafter, the main scan in the print processing of the print head is also referred to as “pass”). On the other hand, the raster line R2 in which squares described as “C, D” are arranged in the main scanning direction shown in the ejection nozzle determination table M2 is the nozzle NZ2 belonging to the C row and D row shown in the print head 50 or Ink is ejected from either one of the nozzles NZ3, and ink dots are formed on the print medium in one pass of the print head 50.

  Next, a method of determining “C, D” in the squares of the discharge nozzle determination table M2 as either “C” or “D” will be described. In the present embodiment, the determination of “C” or “D” limits the number of nozzles that simultaneously eject ink in the nozzle rows that are supplied with ink from the ink cartridges 42 and 43 during the printing process. Thus, “C” or “D” is determined. Specifically, the number of nozzles that simultaneously eject ink is limited in the nozzle rows that are supplied with ink from the ink cartridge 42, that is, the A row and the C row. Similarly, the number of nozzles that simultaneously eject ink in the nozzle rows receiving ink supply from the ink cartridge 43, that is, the B row and the D row, is limited. Hereinafter, this restriction on the number of nozzles is also referred to as “nozzle number restriction”.

  FIG. 6 is an explanatory diagram for explaining the restriction on the number of nozzles. In the matrix shown in FIG. 6A, the horizontal axis indicates time (T). The vertical axis represents the nozzle row to which the nozzles ejecting ink belong at each time (T). Hereinafter, the matrix shown in FIG. 6A is also referred to as a time axis matrix Tm. Also, below the time axis matrix Tm, the usage rate of the nozzles is determined from the A column and C column, that is, the nozzle column receiving ink supply from the ink cartridge 42, and the B column and D column, ie, the ink cartridge 43. It is divided into nozzle rows receiving ink supply. The nozzle usage rate in the A row and the C row is expressed as a nozzle usage rate (AC), and the nozzle usage rate in the B row and the D row is expressed as a nozzle usage rate (BD).

  For example, as shown in the time axis matrix Tm in the figure, when T = ta, all the nozzles belonging to the A row and the B row eject ink. The nozzles belonging to the C row and the D row eject ink using half of the nozzles belonging to each row. In this case, assuming that the usage rate when ink is ejected from all the nozzles for one nozzle row (128 nozzles in this embodiment) is 100, the nozzle usage rate (AC) is all the nozzles in the A row. (Nozzle usage rate 100) and half of the nozzles in the C row (nozzle usage rate 50) are combined to give a nozzle usage rate (AC) of 150. Similarly, regarding the nozzle usage rate (BD), all the nozzles in the B row (nozzle usage rate 100) are combined with half the nozzles in the D row (nozzle usage rate 50), and the nozzle usage rate (BD) is 150. It becomes.

  In the lower part of FIG. 6A, the possibility of ink discharge is described under the nozzle usage rate. Whether ink can be ejected indicates whether ink can be ejected normally from each nozzle (“◯” in the figure) or not (“x” in the figure) with respect to the value of the nozzle usage rate. . When the nozzle usage rate greatly exceeds 150, the total amount of ink ejected from each nozzle receiving ink from one cartridge (for example, ink cartridge 42) at the timing of ejecting ink is determined from one cartridge. The probability of exceeding the total amount of ink supplied to each nozzle increases, and the possibility of ink ejection failure increases. That is, a so-called refill delay of ink tends to occur. In the case of the time axis matrix Tm in FIG. 6A, since the values of the nozzle usage rate (AC) and the nozzle usage rate (BD) are 150 at all times T during the printing process, whether or not the nozzles can be discharged is determined. It is “◯” at all times T. In this embodiment, it is certain that the refill delay does not occur if the value of the nozzle usage rate is 150 or less. However, if the nozzle usage rate does not greatly exceed 150, for example, about 170, it is actually. Can be within an allowable range capable of suppressing the refill delay. In addition, when a printing head 50 and an ink supply mechanism different from the present embodiment are employed, the value of the nozzle usage rate that can suppress the refill delay may vary in units of orders.

  In the case of the present embodiment, since the values of the nozzle usage rates of the A row and the B row are all 100 at all times T, by setting the nozzle usage rates of the C row and the D row to 50, At all times T, the values of nozzle usage rate (AC) and nozzle usage rate (BD) are maintained at 150. FIG. 6B shows a matrix obtained by extracting only “C” and “D” in the time axis matrix Tm, and this is called a matrix CDM. As can be seen from the figure, in the matrix CDM in this embodiment, the numbers of “C” and “D” are substantially equal at each time T. That is, as long as the numbers of “C” and “D” are substantially equal at all times T, a matrix CDM having a mode different from that in FIG. 6B can be employed. These will be exemplified in a modification described later. 6A and 6B, the nozzle usage rate (AC) and the nozzle usage rate (BD) are 150 at each time T even if “C” and “D” are interchanged in the time axis matrix Tm. Since the ink can be ejected and the refill delay can be suppressed, the positions where the nozzles belonging to the nozzle row C form ink dots and the positions where the nozzles belonging to the nozzle row D form ink dots Are compatible with each other in addition to being in an exclusive relationship.

  FIG. 7A shows a time axis matrix Tm with a high possibility of refill delay as a comparative example for easy understanding. As shown in the figure, for example, when T = tb, with regard to the nozzle usage rate (AC), all nozzles in the A row (nozzle usage rate 100) and all nozzles in the C row (nozzle usage rate 100) The nozzle usage rate (AC) is 200. On the other hand, regarding the nozzle usage rate (BD), only all nozzles in the B row (nozzle usage rate 100) are used, and ink is not ejected from the nozzles in the D row (nozzle usage rate 0). Becomes 100. In this case, the nozzle usage rate (AC) is significantly higher than 150, and the possibility of refill delay increases, so whether or not ink can be ejected in the A and C columns is determined as “No” (“×”). FIG. 7B shows a matrix CDM corresponding to the time axis matrix Tm of FIG. As can be seen from the figure, the number of “C” and the number of “D” are greatly different at each time T.

  As described with reference to FIGS. 6 and 7, in order to suppress the refill delay, in this embodiment, “C” and “D” of the discharge nozzle determination table M <b> 2 are determined based on the time axis matrix Tm illustrated in FIG. 6. To decide. Specifically, the timing and landing position of ink ejection from the nozzle, such as the time axis matrix Tm, the scanning speed of the print head in the main scanning direction, the landing time and the landing position of the ink discharged from the nozzle to the print medium, and the like. The discharge nozzle determination table M2 is created in consideration of the parameters comprehensively. The discharge nozzle determination table M2 is stored in the ROM 23 when the printing apparatus 10 is manufactured.

  Here, the description returns to the discharge nozzle determination process. In the ejection nozzle determination process (FIG. 4: step S108), the above-described ejection nozzle determination table M2 is applied to each pixel of the dot data, and each dot on the dot data is formed with the ink ejected from which nozzle. Decide what to do. As an actual process, data corresponding to the ejection nozzle determination table M2 is added to each pixel data in the dot data.

  Thereafter, the CPU 21 starts printing based on the image data after the discharge nozzle determination process (step S110). When printing is started, the CPU 21 controls the print mechanism unit 30 as a process of the print control unit 28 based on the image data after the discharge nozzle determination processing, such as scanning of the print head 50 and ink discharge from each nozzle NZ. The print image is printed on the print medium P. Then, when the printing of the print image on the print medium P is completed, the CPU 21 ends the printing process.

  As described above, the printing apparatus 10 according to the present embodiment limits the number of nozzles that simultaneously eject ink in the nozzle row that is supplied with ink from the ink cartridges 42 and 43 during the printing process. A discharge nozzle determination process is performed using the discharge nozzle determination table M2 generated in consideration, and a print process is executed. Therefore, it is possible to suppress the possibility of refill delay during the printing process, and as a result, it is possible to suppress ink dot omission and ink landing position errors in the printed image.

  Usually, in order to suppress the refill delay, the printing speed may be changed in consideration of the density of dots in the print data. However, the printing apparatus 10 performs the printing process using the ejection nozzle determination table M2. Therefore, the printing speed can be kept constant regardless of the print data.

  As the correspondence relationship with the claims, the C row and the D row correspond to the first nozzle group in the claims, and the A row and the B row correspond to the second nozzle group in the claims. Correspond.

B. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

(B1) Modification 1:
In the above embodiment, the time axis matrix Tm and the discharge nozzle determination table M2 are generated based on the matrix CDM in the mode shown in FIG. 6A, but the time axis matrix Tm is generated based on the matrix CDM of another mode. The discharge nozzle determination table M2 may be generated. As an example, FIG. 8, FIG. 9, and FIG. 10 show matrices CDMa, CDMb, and CDMc that can suppress refill delay, respectively. That is, when the values of the nozzle usage rates of the A row and the B row are preset as the nozzle usage rate 100 at all times T, “C” and “D” at all times T in the matrix CDM. A matrix CDM in which the numbers are substantially equal can be employed. Even when the time axis matrix Tm is generated based on the matrixes CDMa, CDMb, and CDMc in such a manner and used in the printing process, the refill delay can be suppressed and the printing speed can be kept constant regardless of the print data.

(B2) Modification 2:
In the above embodiment, the print head 50 and the ink supply mechanism are the modes shown in FIGS. 2 and 3. However, the present invention is not limited to this, and other print head configurations and ink supply mechanisms can be employed. . An example thereof is shown in FIGS. In the aspect 1 shown in FIG. 11, the nozzle unit 52a includes four nozzle rows. Of the four nozzle rows of the nozzle unit 52a, two rows are supplied with ink from the ink cartridge 42a, and the remaining two rows are supplied with ink from the ink cartridge 43a. That is, ink is supplied from each ink cartridge for two nozzle rows. On the other hand, the nozzle unit 53a includes two nozzle rows. Of the two nozzle rows of the nozzle unit 53a, one row is supplied with ink from the ink cartridge 42a, and the remaining one row is supplied with ink from the ink cartridge 43a.

  In addition, FIG. 12 shows an aspect 2 as another print head configuration and ink supply mechanism. As can be seen from FIG. 12, the nozzle unit 52b receives ink for one nozzle row from each of the ink cartridges 42b, 43b, 44b. Similarly to the nozzle unit 52b, the nozzle unit 53b also receives ink for one nozzle row from each of the ink cartridges 42b, 43b, 44b.

  FIG. 13 shows, as an example, a time axis matrix Tm that can be adopted in the mode 2 shown in FIG. Each value of the nozzle usage rate (AD), the nozzle usage rate (BE), and the nozzle usage rate (CF) does not greatly exceed 150 at any time T. Even if the first and second aspects are employed, the same effects as in the above-described embodiment can be obtained.

(B3) Modification 3:
In the above-described embodiment, the case where the printing process is performed by using one type of ink dot in the printing process has been described. However, the printing apparatus 10 performs the printing process by dividing the ink dots having a plurality of types of sizes. Also good. For example, three types of size ink dots, large dots, medium dots, and small dots, can be distinguished. In this case, as the nozzle usage rate described in FIG. 6A, for example, the usage rate when large dot ink is ejected from all the nozzles for one nozzle row (128 nozzles in this embodiment) is 100. When the medium dot ink is ejected from all the nozzles for one nozzle row (128 nozzles), the usage rate is 50, and the small dot ink is drawn from all the nozzles for one nozzle row (128 nozzles). The nozzle usage rate at each time T can be calculated with the usage rate when 25 is discharged as 25. Whether large, medium, or small ink dots are to be ejected can be determined based on the gradation value of each pixel of the print data.

(B4) Modification 4:
In the above embodiment, a part of the functions realized by software may be realized by hardware, or a part of the functions realized by hardware may be realized by software. Further, some of the functions realized by software may be provided in an external device (for example, a computer) connected to the printing apparatus 10. In the above-described embodiment, the printing apparatus 10 is described as a multi-function machine including a scanner and a copy. However, the printing apparatus 10 may be a printing apparatus dedicated to printing processing. In this case, print processing can be performed by acquiring image data from a computer externally connected to the printing apparatus 10. Furthermore, although the printing apparatus 10 includes only black ink as a printing apparatus dedicated to monochrome printing, it may include color ink and color printing separately.

DESCRIPTION OF SYMBOLS 10 ... Printing apparatus 11 ... Scanner part 12 ... Card slot 13 ... Communication connector 14 ... Display 15 ... Operation panel 20 ... Control unit 21 ... CPU
22 ... RAM
23 ... ROM
24 ... Image data acquisition unit 25 ... Monochrome conversion unit 26 ... Halftone processing unit 27 ... Ejection nozzle determination processing unit 28 ... Print control unit 30 ... Printing mechanism unit 32 ... Carriage drive unit 34 ... Conveying unit 40 ... Carriage 41 ... Head unit 42, 42a, 42b, 43, 43a, 43b ... Ink cartridge 50 ... Print head 52, 52a, 52b, 53, 53a, 53b ... Nozzle unit M1 ... Dither mask M2 ... Discharge nozzle determination table R1, R2 ... Raster line Tm ... Time axis matrix NZ, NZ1-3 ... Nozzle CDM, CDMa ... Matrix P ... Printing medium

Claims (5)

A printing apparatus that performs printing upon receiving ink supplied from L (L is an integer of 2 or more) ink cartridges containing ink of the same hue,
A print head provided with a plurality of nozzle rows in which a plurality of nozzles for ejecting ink are arranged in a predetermined direction and spaced apart in a direction intersecting the direction;
The print head is scanned relative to the print medium in a main scanning direction that is a separation direction of the nozzle rows and a sub-scanning direction that is an arrangement direction of the nozzles, and ink is discharged from the nozzles. And a control unit for controlling
The print head is
The L × a row (a is an integer of 1 or more) nozzle rows in which the positions of the arranged nozzles in the sub-scanning direction are the same and have a predetermined correlation in printing by the control from the control unit A row of a first nozzle group comprising a row of nozzles that receive the supply of ink from each of the L cartridges;
L × b (b is an integer of 1 or more) nozzle rows in which the positions of the arranged nozzles in the sub-scanning direction are different from the nozzles belonging to the first nozzle group, the b nozzles Each of the L cartridges, and a second nozzle group consisting of nozzle rows that receive the supply of ink.
The control unit performs a control to limit the number of nozzles that simultaneously eject ink in each of the a + b nozzle rows to which the L ink cartridges supply the ink. The printing apparatus according to claim 1,
Each of the plurality of nozzle rows has the same nozzle pitch in the sub-scanning direction,
The nozzle rows of the first nozzle group and the nozzle rows of the second nozzle group are arranged at positions where the arrangement positions of the nozzles in the sub-scanning direction are different from each other by 1 / (L × b + 1) of the nozzle pitch. Printer. The printing apparatus according to claim 1 or 2, wherein
The printing apparatus, wherein the control unit performs the control so that the formation positions of the ink dots based on the nozzle rows belonging to the first nozzle group are exclusive and compatible between the nozzle rows. A printing apparatus according to any one of claims 1 to 3,
A printing apparatus in which the value of L is 2, the value of a is 1, and the value of b is 1. A printing method using a printing apparatus that performs printing by receiving ink supplied from L (L is an integer of 2 or more) ink cartridges containing ink of the same hue,
The printing apparatus includes a plurality of nozzle rows in which a plurality of nozzles for ejecting the ink are arranged in a predetermined direction so as to be spaced apart from each other in a direction intersecting the direction, and controls the print head and the ejection of ink from the nozzles. The print head that scans in a main scanning direction that is a separation direction of the nozzle rows and a sub-scanning direction that is an arrangement direction of the nozzles relative to a print medium, and the plurality of the print heads L × a rows (a is 1 or more) in which the positions of the arranged nozzles in the sub-scanning direction are the same as each other and have a predetermined correlation in printing by the control from the control unit The first nozzle group that receives the supply of ink from each of the L cartridges, and the position of each of the arranged nozzles in the sub-scanning direction is the first nozzle group. 1 nozzle row The L × b nozzle rows (b is an integer of 1 or more) different from the nozzles each include a second nozzle group that receives the ink from each of the L cartridges. With
A printing method in which printing is performed by limiting the number of nozzles that simultaneously eject ink in each of the a + b nozzle rows to which the L ink cartridges supply the ink.

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